1. Field of the Invention
The invention relates to a vehicular driving support system and vehicular control system is provided with a communication apparatus enabling bi-directional communication between moving objects. More specifically, the invention relates to a vehicular driving support system which uses vehicle-to-vehicle communication to support, with an efficient volume of information, safe driving at intersections at which there is a concentration of objects, such as buildings, which block the transmission of radio-waves, and a vehicular control system which uses the information obtained from the vehicular driving support system.
2. Description of the Related Art
Vehicle control is able to be performed which supports safe driving based on information gathered using, for example, various sensors mounted on the vehicle and radar equipment mounted on the vehicle which detect obstacles around the vehicle. Further, various information, such as that related to traffic congestion, is able to be provided to a running vehicle by communication between roadside equipment located near a road and an on-board device mounted in the vehicle (i.e., roadside-vehicle communication).
Recently, bi-directional communication between vehicles (herein referred to as “vehicle-to-vehicle communication”) has been proposed, wherein it is conceivable to perform control to prevent accidents from occurring by having vehicles exchange information and proceed in coordination with one another. With this bi-directional communication it is also conceivable to indirectly obtain information provided by roadside equipment (such as a sensor that detects the degree of traffic congestion around the vehicle) without direct roadside-vehicle communication by having one vehicle relay information obtained from the roadside equipment to another vehicle.
JP(A) 4-290200 discloses technology using this kind of vehicle-to-vehicle communication. According to this publication, a vehicular warning apparatus is known which estimates the probability of a collision with an intersecting vehicle when crossing an intersection based on information relating to the current position, running speed, and direction of travel of the intersecting vehicle obtained by vehicle-to-vehicle communication, and outputting a warning when necessary in order to prevent a collision with the intersecting vehicle at the intersection.
In the vehicle-to-vehicle communication, both vehicles are provided with a radio transceiver which both transmits a radio signal that includes information relating to the host vehicle and receives a radio signal that includes information relating to the other vehicle. This vehicle-to-vehicle communication is typically between one vehicle and one or more other vehicles. As a result, when there is a concentration of vehicles, it may become difficult for each vehicle to efficiently extract the necessary other vehicle information. Further, the amount of information to be processed increases, thus increasing the processing load.
Therefore, when vehicle-to-vehicle communication is taking place between a vehicle and an unspecified number of other vehicles, or more specifically, at a location where there is a concentration of a plurality of vehicles, such as at an intersection, the processing load on the receiving side increases so time is required to extract the necessary information. As a result, the output timing of a warning to prevent a collision with an intersecting vehicle is delayed, which may reduce the functionality of the vehicle-to-vehicle communication at a place where vehicle-to-vehicle communication is extremely important.
Moreover, some areas may have a concentration of objects, such as buildings, that block the transmission of radio-waves. In this case, because radio-waves in the high frequency band used in vehicle-to-vehicle communication theoretically do not diffract, vehicle-to-vehicle communication between vehicles (e.g., vehicles which will meet at an intersection) providing important information may be impeded when there are radio-wave blocking objects present. On the other hand, it is possible to use information obtained indirectly via vehicle-to-vehicle communication with another vehicle. However, near intersections where there is a concentration of vehicles, it is still difficult to extract and apply the information quickly, as described above. Also in this case, even at intersections where there are actually no radio-wave blocking objects that impede vehicle-to-vehicle communication, the processing load on the receiving side still increases due to the indirect information provided by the other vehicle.